1. Technical Field
The present invention relates to a discharge lamp lighting device that drives a discharge lamp to turn on the discharge lamp, a projector, and a method for driving a discharge lamp.
2. Related Art
In lighting devices for discharge lamps used as light sources for projectors and the like, various techniques of giving a change in drive waveform to stabilize the arc position have been proposed. In a lighting device described in, for example, Japanese Patent No. 3741727 (Patent Document 1), a short current pulse is superimposed on an alternating rectangular wave current to be supplied to a discharge lamp in synchronization with the current. Using such a technique makes it possible to suppress flicker caused when the arc position is unstable.
However, superimposing a current pulse as described above causes electric power to be supplied to the discharge lamp, that is, the brightness of the discharge lamp to change periodically. Therefore, when a light source of a projector is turned on with the lighting device described in Patent Document 1, there is a problem in that stripe noise (scroll noise) occurs due to a deviation between a period of changing the brightness of the discharge lamp and a period of generating a screen (frame period).